public class onceNum {
    public static void main(String[] args) {
        int []arr={1,1,33,33,5,534,534};
        System.out.println(onceNum(arr));
    }

    public static int onceNum(int[]array){
        int ret=0;
        for (int i:array) {
            ret=ret^i;
        }
        return ret;
    }
}
